lecture

Question 1

Functions of the Skeletal System:

Answer 1

1. Support
   The bones form the body’s supporting framework.
2. Protects vital organs such as the brain, the heart and lungs.
3. Movement
   As muscles contract, they pull on bones and therefore,
   move them.
   4.Hemopoiesis/Hematopoiesis – blood cell formation in the red bone marrow
4. Storage of calcium and phosphorus
   Calcitonin, secreted by the thyroid gland, enhances incorporation of calcium into bone.
   Parathyroid hormone, secreted by the parathyroid gland, regulates the release of calcium from bone.

Question 2

Types Of Bones - According To Shape

Answer 2

1. Long Bones - longer than wide
   Examples: femur, humerus
2. Short Bones – roughly with equal dimensions of length and width
   Example: carpal bones
3. Flat Bones - thin and broad
   Example: skull bones
4. Irregular Bones - with complex shape
   Example: vertebral bones
5. Sesamoid Bone – small, round bone embedded within a tendon
   Example: patella

Question 3

Structure Of A Long Bone

Answer 3

1. Diaphysis
   shaft of long bone hollow tube made of hard, compact bone but light in weight to permit easy movement
2. Medullary Cavity
   hollow area inside the diaphysis containing yellow fat bone marrow

3.Epiphysis – expanded ends of long bones composed of spongy bone with red bone marrow
4. Articular Cartilage – thin layer of cartilage covering the epiphyses
acts as a cushion between bones in a joint
5. Periosteum- strong fibrous membrane covering the shaft of long bones
6. Endosteum –membrane that lines the medullary cavity

Question 4

What are the 2 major types of connective tissues in the bone:

Answer 4

1. Compact Bone - the hard and dense outer layer of bone
2. Spongy Bone – the porous or cancellous bone at the ends of long bones
   . Trabeculae (Latin “trabeculae” – small beam) – needle-like threads of spongy bone

Question 5

What is an Osteon also called Haversian

Answer 5

Osteon or Haversian system– the smallest functional and structural unit of compact bone

. Each circular, tube-like osteon has a central canal that contains a blood vessel. Layers of calcified circular matrix around the central canal are called concentric lamellae (Latin “lamella”- layer)

. Osteocytes or bone cells lie in between lamellae inside little spaces called lacunae (Latin “lacuna” – hole, pit)

.Canaliculi or tiny passageways from the central canal - supply food and oxygen to the osteocytes; connect the osteocytes

Question 6

What is concentric lamellae?

Answer 6

Layers of calcified
circular matrix around the central canal are called
concentric lamellae

Question 7

What is an Osteocytes also called bone cells

Answer 7

Osteocytes or bone cells lie in between lamellae inside little spaces called lacunae (Latin “lacuna” – hole, pit)

Question 8

Canaliculi or tiny passageways from the central canal

Answer 8

• supply food and oxygen to the osteocytes; connect the osteocytes

Question 9

What is CARTILAGE & where are chondrocytes located?

Answer 9

– connective tissue with collagenous fibers imbedded in firm gel matrix

.Chondrocytes – cartilage cells that are located in lacunae
.Lack of blood vessels in cartilage makes post injury healing rather slow

Question 10

Endochondral Ossification

Answer 10

– formation of bone
from cartilage

. Begins before birth of an infant wherein calcium is laid on cartilage by bone-forming cells called osteoblasts
. Blood vessels invade the diaphysis and ossification centers appear in epiphyses
. Simultaneous action of the osteoclasts, bone-reabsorbing cells, helps sculpture bone into its adult size and shape

Question 11

Epiphyseal Plate (growth plate) & Epiphyseal line

Answer 11

– contains cartilage
from where bone continues to develop and grow

Epiphyseal Line - results when the epiphyseal
plate has ossified with the
resultant cessation of bone
growth

Question 12

Bone Repair

Answer 12

After a fracture, bones heal as long as the circulatory
supply and cellular components of the periosteum and
endosteum survive.

Stages of Healing of a Simple Bone Fracture:
1. Hematoma Formation
2. Fibrocartilagenous callus
3. Bony callus-formation
4. Remodeling

Question 13

Hematoma Formation (Bone Repair)

Answer 13

Blood vessels are broken causing bleeding, pooling and clotting of blood into the fractured bone – a fracture hematoma is formed.

Question 14

Fibrocartilagenous callus formation (Bone Repair)

Answer 14

formation. Cells from the
periosteum and endosteum migrate into the fracture zone. These cells (fibroblasts) convert into osteoblasts which,
together with the osteoclasts,begin reconstruction of
bone.The cells form a thickening (callus) around the fractureand some transform into cartilage-producing cells.
Capillaries grow in the fracture site.

Question 15

Bony callus-formation (Bone Repair)

Answer 15

Continued migration and proliferation of osteoblasts and osteocytes result in turning the fibrocartilagenous callus into bony callus.

Question 16

Remodeling (Bone Repair)

Answer 16

The bony callus will smoothen and be
remodeled through the action of the osteoclasts.

After repair, the fractured bone will be “good as
new” although slightly thicker than normal.

Question 17

Axial Skeleton

Answer 17

-bones at the center or the axis of the body; includes the skull, spine, chest and hyoid bone

Question 18

Appendicular Skeleton

Answer 18

• bones of the upper and lower extremities (appendages) including the pectoral and pelvic girdles

Question 19

Bones of the Axial Skeleton

Answer 19

1. Frontal Bone – forehead bone
2. Parietal Bones (Latin “parietalis” –wall of a cavity) form the topsides or roof of the cranium
3. Temporal Bones – form the lower sides of the cranium; contain the middle and inner ears
4. Occipital Bone (Latin “occiput” – posterior and inferior) – bone forming the back of the skull
5. Sphenoid Bone –forms central part of floor of cranium; forms the sella turcica which holds the pituitary gland
6. Ethmoid Bone - uniquely-shaped bone that forms floor of cranium, part of the orbit, sidewalls and roof of the nose and part of its middle partition

Question 20

Bones of the Face

Answer 20

1. Zygomatic bone(Greek “zygoma” - yoke) - cheek bone
2. Maxilla – upper jaw
3. Mandible – lower jaw
4. Nasal – bones that form the upper part of bridge of nose
5. Lacrimal – medial wall of eye socket and side wall of nasal cavity
6. Vomer – forms lower, back part of nasal septum

Question 21

The Vertebral (Spinal)Column:
Total bones of spinal column = 26

Answer 21

7 Cervical Bones – Atlas (1st cervical), Axis (2nd cervical)
12 Thoracic - upper back
5 Lumbar - lower back
5 Sacral bones fused into one among adults to form the sacrum
3-5 Coccygeal bones fused into one among adults to form the tailbone

Question 22

thoracic cage or
chest cage

Answer 22

is made up of the 12 pairs of
ribs, the sternum and the thoracic vertebrae.

.The first 7 pairs of ribs are true ribs. They are attached
to the sternum by costal cartilages.
.The lower 5 pairs are false ribs. The 8th, 9th and 10th
ribs are attached to the sternum through the costal
cartilage of the 7th rib.
.The 2 last pairs that are not attached to the sternum (11th and 12th) are floating ribs.

Question 23

Sternum

Answer 23

1. manubrium -
   uppermost part
   attached to the
   clavicle
2. body - of the
   sternum
3. xiphoid -
   process

Question 24

Appendicular Skeleton

Answer 24

The bones of upper and lower extremities together
with the pectoral and pelvic girdles comprise
the appendicular skeleton.

The pectoral girdle - attaches the bones of the upper extremities to the axial skeleton. The scapula (shoulder blade) and the clavicle (collar bone) comprise the
pectoral girdle.

Question 25

sternoclavicular joint

Answer 25

is the point of attachment between the bones of the pectoral girdle and the axial skeleton

Question 26

Bones of the Upper Extremities

Answer 26

Humerus – arm bone Radius – forearm bone on the side of the thumb Ulna – forearm bone on the side of the little finger Carpal Bones –wrist bones, 8 on each wrist Metacarpals – bones of the palm, 5 on each hand Phalanges – finger bones, 14 on each hand

Question 27

The Pelvic Girdle

Answer 27

The pelvic girdle attaches the bones of the lower extremity to the axial skeleton. The ilium, ischium and pubis comprise the pelvic girdle (hip). The pelvic girdle is attached to the axial skeleton through the sacrum. The femur (thigh bone) is attached to the pelvic girdle through the acetabulum, a socket at the hip joint formed by the three hip bones.

Question 28

iliosacral joint

Answer 28

iliosacral joint attaches bones of the lower extremities to the axial skeleton.

Question 29

Bones of the Lower Extremity

Answer 29

Femur – thigh bone; longest, strongest bone of the body Tibia – shinbone Fibula – calf bone Patella – knee cap Tarsal bones – bones of the ankle joint, 7 on each ankle Metatarsal bones – foot bones, 5 on each foot Phalanges – toe bones, 14 on each foot

Question 30

JOINTS (ARTICULATIONS)

Answer 30

.Connection of a bone to another bone .Hold bones together securely while making movements possible

Question 31

Three types of joints according to the degree of movement they allow:

Answer 31

1. Synarthroses – no movement 2. Amphiarthroses – slight movement 3. Diarthroses – free movement

Question 32

Synarthrosis

Answer 32

fibrous connective tissue grows in between the articulating bones; no movement is allowed Example: skull joints (sutures) coronal suture sagittal suture lambdoidal suture squamous suture

Question 33

Amphiarthrosis

Answer 33

.cartilage connects the articulating bones .some movement is allowed Examples: symphysis pubis, joint between vertebral bones

Question 34

Diarthrosis

Answer 34

–freely movable joints with the following structural features: . Joint capsule . Joint cavity . Articular cartilage . Ligaments . Synovial Membrane . Bursa . meniscus (meniscus - crescent)

Question 35

Joint capsule

Answer 35

– toughest fibrous connective tissue that securely joins the bones in a joint

Question 36

Joint cavity

Answer 36

– space inside the capsule lined with synovial membrane that secretes synovial fluid

Question 37

Articular cartilage

Answer 37

– covers the ends of the bones acting as rubber cushion to absorb shock and help reduce friction during movement Examples: knee joint, elbow joint

Question 38

Ligaments

Answer 38

– cords similarly made of strongest fibrous connective tissue growing out of the periosteum, securing the bones together more firmly

Question 39

Synovial Membrane

Answer 39

– lines the joint space and secretes synovial fluid that acts like a lubricant allowing easier joint movement with less friction

Question 40

Bursa

Answer 40

– a fluid-filled pouch-like extension of the synovial membrane that acts like a shock-absorbing cushion in the joint

Question 41

meniscus (meniscus – crescent)

Answer 41

is a shock-absorbing fibrocartilage pad lying between 2 opposing articular surfaces. . Increases the area of contact between bones . Distributes pressure better . Limits extreme movements

Question 42

Types of Diarthrotic Joints

Answer 42

. Gliding joint . Hinge Joint . Saddle joint . Pivot joint . Condyloid joint . Ball-and-Socket Joint

Question 43

Gliding joint

Answer 43

– least movable, allows limited gliding movements Example: joint between the clavicle and the manubrium

Question 44

Hinge Joint

Answer 44

– allows movement on only 2 directions – flexion and extension -- like opening and closing of a door Example: knee joint, elbow joint, finger joints

Question 45

Saddle joint

Answer 45

The only saddle joint in the body is between the first metacarpal bone and the trapezium of the carpal joint. - Allows flexion, extension, abduction, adduction and circumduction so that the thumb may be opposed to the fingers

Question 46

Pivot joint

Answer 46

Where a small projection of one bone pivots in an arch of another bone allowing pivotal (rotational) movement of the joint Example: joint between the atlas (first cervical vertebra) and the axis (second cervical vertebra)

Question 47

Atlas (C1) and Axis (C2)

Answer 47

The configuration and relationship between the atlas and axis allow the head to attain rotational movement.

Question 48

Condyloid joint

Answer 48

Where the condyloid (oval projection) of a bone fits into an elliptical socket. Example: joint between radius and carpal bones

Question 49

Ball-and-Socket Joint

Answer 49

– the ball-shaped head of one bone fits into a concave socket of another bone - allows the widest range of movement Example: hip joint, shoulder joint

Question 50

Disorders of Bones

Answer 50

1. Fracture 2. Osteoporosis 3. Osteomyelitis 4. Bone Tumors

Question 51

Fracture

Answer 51

– a break in bone often caused by high impact or stress on bone - may likewise be caused by medical conditions like osteoporosis, cancer or osteogenesis imperfecta

Question 52

Osteoporosis

Answer 52

– a bone disease of advancing age characterized by loss of calcified matrix and collagenous fibers from bone - reduction in new bone growth results in bone degeneration and “spontaneous fractures”

Question 53

Osteomyelitis

Answer 53

– inflammation of the bone and bone marrow usually due to a bacterial infection - may occur as a complication of trauma or surgery, or may be blood-borne from another body site

Question 54

Bone Tumors

Answer 54

– mass of tissue that is formed when bone cells proliferate uncontrollably Most bone tumors are benign. 1. Osteochondroma 2. Osteoid Osteoma 3. Osteosarcoma ( Osteogenic Sarcoma) 4. Chondrosarcoma 5. Abnormalities in Spinal Curvatures Scoliosis 6. Skeletal Changes in Aging aside from Osteoporosis 6.1 Lipping 6.2 Osteoarthritis

Question 55

Osteochondroma

Answer 55

– most common benign bone tumor that usually develops during childhood and adolescence - caused by overgrowth of bone and cartilage cells near the growth plat

Question 56

Osteoid Osteoma

Answer 56

– benign tumor that arises from the osteoblasts, occurring mostly in long bones - peak age incidence is during the early twenties

Question 57

Osteosarcoma ( Osteogenic Sarcoma)

Answer 57

– most common malignant tumor of bone caused by proliferation of osteoblasts - teenagers are the most commonly affected age group

Question 58

Chondrosarcoma

Answer 58

– bone cancer that begins from cartilage cells - often affecting people between 40 and 70 years

Question 59

Abnormalities in Spinal Curvatures Scoliosis

Answer 59

- sideways curve of the spine that usually assumes an ‘S’ or a ‘C’ shape Kyphosis –abnormally rounded upper curvature of the spine Lordosis (Swayback)– spine curves inward at the lower back

Question 60

Lipping

Answer 60

– a process wherein aging bones develop indistinct, shaggy-appearing margins with spurs - restricts movement because of piling up of bone tissue around the joints

Question 61

Osteoarthritis

Answer 61

– degenerative joint disease caused by inflammation, breakdown and eventual loss of cartilage in joints

Question 62

Disorders of Joints

Answer 62

1. Dislocation (Luxation) 2. Sprain 3. Arthritis -Osteoarthritis -Rheumatoid Arthritis -Gouty Arthritis or Gout 4. Disorders of the Intervertebral Discs - Degenerative Disc Disease - Disc Herniation 5. Bursitis

Question 63

Dislocation (Luxation)

Answer 63

- when bones in a joint become displaced or misaligned usually caused by sudden impact to the joint

Question 64

Sprain

Answer 64

– joint injury caused by violent twisting of a ligament

Question 65

Arthritis – joint inflammation

Answer 65

Osteoarthritis – degenerative joint disease caused by inflammation, breakdown and eventual loss of cartilage in joints Rheumatoid Arthritis – a chronic autoimmune disease with an unknown cause Gouty Arthritis or Gout – joint inflammation due to excessive amounts of uric acid that form crystals in joints

Question 66

Disorders of the Intervertebral Discs

Answer 66

. Degenerative Disc Disease – a natural part of aging when the disc undergoes structural deterioration, loses ability to cushion the vertebrae - may not cause pain or may cause intractable back pain . Disc Herniation – occurs when the disc prolapses out of its anatomical position due to injury or aging - can cause back or neck pain, numbness or tingling in the arms, or searing pain down one or both legs

Question 67

Bursitis

Answer 67

– inflammation of a bursa caused by irritation, injury or infection